package com.xxhong.xxtv.utils;

import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

public class RSACoder {
	// 非对称密钥算法
	public static final String KEY_ALGORITHM = "RSA";
	/**
	 * 密钥长度，DH算法的默认密钥长度是1024 密钥长度必须是64的倍数，在512到65536位之间
	 * */
	private static final int KEY_SIZE = 512;
	// 公钥
	private static final String PUBLIC_KEY = "xxhong_public_key";

	// 私钥
	private static final String PRIVATE_KEY = "xxhong_private_key";

	/**
	 * 初始化密钥对
	 * 
	 * @return Map 甲方密钥的Map
	 * */
	public static Map<String, Object> initKey() throws Exception {
		// 实例化密钥生成器
		KeyPairGenerator keyPairGenerator = KeyPairGenerator
				.getInstance(KEY_ALGORITHM);
		// 初始化密钥生成器
		keyPairGenerator.initialize(KEY_SIZE);
		// 生成密钥对
		KeyPair keyPair = keyPairGenerator.generateKeyPair();
		// 甲方公钥
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		// 甲方私钥
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
		// 将密钥存储在map中
		Map<String, Object> keyMap = new HashMap<String, Object>();
		keyMap.put(PUBLIC_KEY, publicKey);
		keyMap.put(PRIVATE_KEY, privateKey);
		return keyMap;
	}

	/**
	 * 私钥加密
	 * 
	 * @param data待加密数据
	 * @param key
	 *            密钥
	 * @return byte[] 加密数据
	 * */
	public static byte[] encryptByPrivateKey(byte[] data, byte[] key)
			throws Exception {

		// 取得私钥
		PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 生成私钥
		PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
		// 数据加密
		Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
		cipher.init(Cipher.ENCRYPT_MODE, privateKey);
		return cipher.doFinal(data);
	}

	/**
	 * 公钥加密
	 * 
	 * @param data待加密数据
	 * @param key
	 *            密钥
	 * @return byte[] 加密数据
	 * */
	public static byte[] encryptByPublicKey(byte[] data, byte[] key)
			throws Exception {

		// 实例化密钥工厂
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 初始化公钥
		// 密钥材料转换
		X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
		// 产生公钥
		PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);

		// 数据加密
		Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
		cipher.init(Cipher.ENCRYPT_MODE, pubKey);
		return cipher.doFinal(data);
	}

	/**
	 * 私钥解密
	 * 
	 * @param data
	 *            待解密数据
	 * @param key
	 *            密钥
	 * @return byte[] 解密数据
	 * */
	public static byte[] decryptByPrivateKey(byte[] data, byte[] key)
			throws Exception {
		// 取得私钥
		PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 生成私钥
		PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
		// 数据解密
		Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
		cipher.init(Cipher.DECRYPT_MODE, privateKey);
		return cipher.doFinal(data);
	}

	/**
	 * 公钥解密
	 * 
	 * @param data
	 *            待解密数据
	 * @param key
	 *            密钥
	 * @return byte[] 解密数据
	 * */
	public static byte[] decryptByPublicKey(byte[] data, byte[] key)
			throws Exception {

		// 实例化密钥工厂
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 初始化公钥
		// 密钥材料转换
		X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
		// 产生公钥
		PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);
		// 数据解密
		Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
		cipher.init(Cipher.DECRYPT_MODE, pubKey);
		return cipher.doFinal(data);
	}

	/**
	 * 取得私钥
	 * 
	 * @param keyMap
	 *            密钥map
	 * @return byte[] 私钥
	 * */
	public static byte[] getPrivateKey(Map<String, Object> keyMap) {
		Key key = (Key) keyMap.get(PRIVATE_KEY);
		return key.getEncoded();
	}

	/**
	 * 取得公钥
	 * 
	 * @param keyMap
	 *            密钥map
	 * @return byte[] 公钥
	 * */
	public static byte[] getPublicKey(Map<String, Object> keyMap)
			throws Exception {
		Key key = (Key) keyMap.get(PUBLIC_KEY);
		return key.getEncoded();
	}
}
